Regarding fees for tax purposes.

On my main exchange (Bitflyer) my fees are paid in BTC for BTC/JPY trades. How are these fees converted to JPY?

1) The total fees are summed and then converted to JPY at the end of the tax year using some reference exchange rate?
2) The fees are converted to JPY using the trade price and then summed?

Clearly option 2 is more accurate as BTC has risen significantly in value during 2017. I can manually do this using excel but perhaps you already do this? I ask because my trade fees on this exchange are very large (>1000$).

Lots of fans of CoinTracking here in Japan. Would love Bitflyer support!